Ai editor to change the facial expression in a video?

I created an ai video of a person speaking but it doesn’t look 100% realistic because the person is sort of smiling slightly the entire time. I want to make the facial expression neutral to look more natural but I’ve been searching multiple ai editing sites and I haven’t been able to find any that you can upload a video and edit the facial expression. Canva is the closest I’ve gotten but the expression changer is only allowed for photos not videos.